Move mkdir(1) to toybox.

Test: treehugger
Change-Id: I5fcbf33acb93cdc279a900586b96e0232c4aea87
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index bd810f2..592c2eb 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -105,7 +105,6 @@
 	"lsof":      Allowed,
 	"m4":        Allowed,
 	"md5sum":    Allowed,
-	"mkdir":     Allowed,
 	"mktemp":    Allowed,
 	"mv":        Allowed,
 	"openssl":   Allowed,
@@ -163,6 +162,7 @@
 	"env":      Toybox,
 	"head":     Toybox,
 	"id":       Toybox,
+	"mkdir":    Toybox,
 	"od":       Toybox,
 	"paste":    Toybox,
 	"pwd":      Toybox,